Model Q46C4 4E-Conductivity Monitor from ATI


The Q46C4 4E conductivity monitor is the answer for monitoring almost any water based process. Drinking water, plating bath solutions, cooling water, process wash water or virtually any other aqueous system can be monitored accurately and reliably. The unique drive/control scheme used in the 4 electrode system allows a single sensor configuration to be used in conductivity ranges from 0-200 uS to as high as 0-2,000 mS (0-2 S). For chemical mixing application, a concentration display can be selected.

While the theory of monitoring conductivity is simple, in practice it can be very frustrating. While simple 2-electrode sensors are inexpensive and can provide accurate data, continuous monitoring of even relatively clean water can foul the electrodes and degrade the measurement.

Maintaining accuracy is made more difficult when the amount of solids dissolved in the process varies over a wide concentration range.

In a traditional 2-Electrode sensor, each electrode performs two functions. The electrodes are used to carry the AC drive voltage and also measure the current flow due to the conductivity of the water. This type of sensor has a limited conductivity range and is affected by electrode coating. In addition, changes in cable resistance and capacitance can cause measurement errors.

A 4-Electrode sensor provides two sets of electrodes, one set to carry the AC drive voltage and a separate set to sense the strength of the electric field between electrodes. This allows the drive voltage to be automatically adjusted for changes in electrode condition and allows the monitor to automatically correct for the effects of electrode fouling. It also allows the sensor to measure accurately over a very wide range of conductivity and eliminates errors due to changes in cable length.

Sensors the the Q46C4 system are available in a variety of mounting configuration: convertible style with 1″ NPT threads for pipe or tank mounting, 1½” or 2″ sanitary style fittings in 316 stainless steel and insertion system for 1¼” NPT hot tap assemblies that allow the sensor to be removed from service without shutting down the process. Flor low flow bypass applications, a Noryl sensor with quick disconnect cable and acrylic flowcell are available.


  • Concentration version for direct display of chemical concentrations
  • Two isolated 4-20 mA outputs are standard, with an option for a third output if required. Default setting provides analog outputs for conductivity and temperature.
  • Expansion board to add a third 4-20 mA analog output
  • Wide range capability with selectable ranges of 0-2,000 uS up to 0.2000 S, provides maximum application flexibility
  • Power options include universal 100-240 VAC, 0or 12-24 VDC
  • Standard PID control function assignable to one analog output
  • Available in either Profibus-DP, Modbus-RTY or Ethernet-IP
  • Three SPDT relays are standard, with relay functions programmable for alarm, control or trouble indication. Three additional low power relays available as an option
  • NEMA 4X enclosure is suitable for wall, pipe or panel mounting
  • Back lit large LCD display provides clear visibility in any lighting conditions. A scrolling second line on the display provides additional information and programming prompts.

Conductivity monitors can be used to measure and display the concentration of acids or bases used in various chemical process applications. The Q46C4 is available with pre-loaded tables allowing direct display of concentration for solutions of sodium chloride (NaCl), hydrochloric acid (HCl), potassium hydroxide (KOH) and sodium hydroxide (NaOH).

In addition to these standard tables, the user may enter their own table data for other chemicals or may edit the standard tables supplied. Custom tables require data on both concentration vs conductivity and temperature vs conductivity for the chemical of interest.

Specifications – Monitor

Measuring Range 0 to 200.0 uS; 0 to 2.00, 20.00, 0.0 to 200.0 to 2,000 mS, 0-2.000 S
Accuracy ±0.5% or selected range
Repeatability 0.3% of selected range
Non-Linearity 0.1% of selected range
Temperature Drift 0.01% of span/°C
Display Large 4 digit main display, 0.75″ characters, 12 digit alpha numeric second line display
Power 100-240 VAC ±10%, 50/60 Hz, 10 VA maximum, 12-24 VDC, 500 mA maximum
Relays Three SPDT, contacts rated 6 amp@250 VAC, 5 amp @25 VDC, 3 additional low power SPST non-isolated relays optional
Digital Ouput Profibus-DP, Modbus-RTU, Ethernet-IP
Analog Outputs Two Isolated 4-20 mA, 550 ohm max load
Sensitivity 0.05% of span
Temperature -20 to 60°C
Mounting Wall mounting kit standard, Panel mount bracket and pipe u-bolts available
Weight 2 wire or battery unit: 6 pounds
Enclosure NEMA 4X (IP-66) polycarbonate, V-0 flammability

Specifications – Sensors

Sensors 4-Electrode
Materials PEEK with titanium electrodes
Cable Length 15′ standard, 60′ maximum with junction box
Temperature Limits -10 to 125°C
Pressure Limits 0-100 psig
Connection 1″ NPT for convertible style
Flowcell Sensor 1 ¼” NPT with quick disconnect cable

Ordering Information

Other configurations available For pricing, please call AFC International at 1-800-952-3293, 219-987-6825 or fax 219-987-6826 or email


Q46C4 4E Conductivity Monitor literature

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